<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
<form action="#" method="get" autocomplete="on">
    <lable for="us">用户名:  </lable>
   <input type="text" name="username" placeholder="在此输入用户名" required id="us">
    <button type="submit">提交啊</button>
</form>
</body>
</html>